1,767 research outputs found

    The effect of a centenary storm on the long-lived seagrass Posidonia oceanica

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    We used the disturbance resulting from a once in a 100‐yr storm on the northwest Mediterranean coast to examine the extent of the disturbance, the tolerance thresholds to burial, and the medium‐term response of the long‐lived Posidonia oceanica seagrass. Sediment burial at 12 surveyed areas was particularly strong in shallow meadows, with 23% of their surfaces buried, on average, under more than 10 cm of sediment. In contrast, less than 5% of the meadow was affected at deeper locations. At three sites, we tracked short‐term mortality along a gradient of sediment burial. Survival response to burial was clearly nonlinear, with a significant threshold at 4-5 cm, beyond which shoot mortality was 100%. To track medium‐term potential recovery, we established permanent plots subject to three sediment burial levels (0-5, 5-10, and > 10 cm burial) in four meadows. Where the initial shoot mortality was 100%, we recorded no shoot recovery over the 4‐yr period. In the remaining plots, where some shoots remained alive, we detected either further mortality or shoot recovery of 7% per year on average. Extreme storm events can result in sudden catastrophic losses of seagrass cover in shallow P. oceanica meadows. In the long term and due to the long return time of such storms, the species may still be able to recover despite its low recovery potential. However, added anthropogenic stressors, including climate change, may seriously test the ability of long‐lived shallow seagrass ecosystems to resist high‐intensity natural disturbances and may be critical for its persistence

    Detecting the impacts of harbour construction on a seagrass habitat and its subsequent recovery

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    Managing coastal development requires a set of tools to adequately detect ecosystem and water column degradation, but it also demands tools to detect any post-disturbance improvement. Structural seagrass indicators (such as shoot density or cover) are often used to detect or assess disturbances, but while they may be very sensitive to the impact itself, it is unclear if those indicators on their own can effectively reflect recovery at time scales relevant to managers. We used the construction of a harbour affecting a nearby Posidonia oceanica seagrass community to test the ability of a set of indicators (structural and others) to detect alterations and to evaluate their sensitivity to recovery of environmental quality after harbour construction was complete and the disturbance ceased. We used a Beyond Before After Control Impact (BBACI) design to evaluate effects on one impacted and three control meadows where we used structural, morphological, community and physiological indicators (26 in total) to asses disturbance impacts. Additionally, we measured some of the potential environmental factors that could be altered during and after the construction of the harbour and are critical to the survival of the seagrass meadow (light, sediment organic matter, sediment accrual). Harbour construction caused a clear increase in sediment organic matter and in sediment deposition rates, especially fine sand. Light availability was also reduced due to suspended sediments. Sediment and light conditions returned to normal levels 5 and 15 months after the construction began. As expected, seagrass structural indicators responded unequivocally to these environmental changes, with clear reductions in shoot density. Additionally, reduced light conditions quickly resulted in a decline in carbohydrate content in affected meadows. Unexpectedly, we also recorded a significant increase in metal content in plant tissues. No response was detected in the physiological indicators related to eutrophication (e.g. N and P content in tissues) and in morphological (shoot biomass) and community (epiphyte biomass) indicators. More than three years after the completion of the harbour, structural indicators did not show any sign of recovery. In contrast, physiological indicators, mainly heavy metal and carbohydrates content, were much better in detecting the improvement of the environmental conditions over the fairly short period of this study. These results indicate that while structural indicators are critical to evaluate the immediate effect of disturbances and the recovery on impacted systems, specific physiological indicators may be much better suited to determining the timing of environmental quality recovery. The design of impact and monitoring protocols in the wake of coastal developmental projects need to consider the differential effectiveness and time-response of measured indicators carefully

    Differences in predator composition alter the direction of structure‐mediated predation risk in macrophyte communities

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    Structural complexity strongly influences the outcome of predator-prey interactions in benthic marine communities affecting both prey concealment and predator hunting efficacy. How habitat structure interacts with species‐specific differences in predatory style and antipredatory strategies may therefore be critical in determining higher trophic functions. We examined the role of structural complexity in mediating predator-prey interactions across several macrophyte habitats along a gradient of structural complexity in three different bioregions: western Mediterranean Sea (WMS), eastern Indian Ocean (EIO) and northern Gulf of Mexico (NGM). Using sea urchins as model prey, we measured survival rates of small (juveniles) and medium (young adults) size classes in different habitat zones: within the macrophyte habitat, along the edge and in bare sandy spaces. At each site we also measured structural variables and predator abundance. Generalised linear models identified biomass and predatory fish abundance as the main determinants of predation intensity but the efficiency of predation was also influenced by urchin size class. Interestingly though, the direction of structure‐mediated effects on predation risk was markedly different between habitats and bioregions. In WMS and NGM, where predation by roving fish was relatively high, structure served as a critical prey refuge, particularly for juvenile urchins. In contrast, in EIO, where roving fish predation was low, predation was generally higher inside structurally complex environments where sea stars were responsible for much of the predation. Larger prey were generally less affected by predation in all habitats, probably due to the absence of large predators. Overall, our results indicate that, while the structural complexity of habitats is critical in mediating predator-prey interactions, the direction of this mediation is strongly influenced by differences in predator composition. Whether the regional pool of predators is dominated by visual roving species or chemotactic benthic predators may determine if structure dampens or enhances the influence of top-down control in marine macrophyte communities

    Fatty Acids in the Meat of Buffaloes Supplemented with Fish Oil

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    The purpose of this study has been to investigate the influence of both a supplementary fish oil diet on conjugated linoleic acid (CLA) and n6 and n3 fatty acids on intramuscular fat in Mediterranean buffalo meat. Twenty animals were randomly divided into two groups and fed with Brachiaria brizantha, 3Kg rice bran, 500 g corn and 500 g sunflower pellets for 60 days. Group I received this diet only while in group II each animal received additional 100 ml fish oil daily. Results indicated a significant decrease of palmitic fatty acid in group II (232.67 mg/g fat) in relation to group I (254.73 mg/g fat). Among unsaturated acids (AGI), the 9c 11t CLA value of group II (21.23 mg/g fat) showed an increase in relation to group I (15.80 mg/g fat), while the linoleic acid content of group II (28,85 mg/g fat) decreased significantly in relation to group I (47,00 mg/g fat). However, the alpha linolenic acid showed no significant difference between the supplemented diet group and the control group (10.31 and 10.70 mg/g fat, respectively). Group II n6/n3 ratio was narrower (2.69:1) than that of group I (4.55:1). Summing up, group II diet, which included fish oil, increased the CLA content in intramuscular fat and decreased the n6 fatty acids, improving the n6/n3 ratio

    AXA: a computer program for the management of the Canary Goat Group milking control programs

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    A computer program, developed in Clipper, for the management of the genealogical and productive information from the Canary Goat Group, is described. The two first sections of this program are planned for the males and females genealogical data arrangement. Third section is devised for the productive data storage. Fourth section is constructed for the emission of reports and finally, fifth section is a miscellaneous of utilities, where the connection with other programs must be highlighted. Also an exit control is enclosed. The basic purposes of this program aim the emission of official production reports for the Administration and farmers, and the information processing for its analysis in programs of genetic selection.Se describe un programa de ordenador, desarrollado en Clipper, para la gestión de la información genealógica y productiva de la Agrupación Caprina Canaria. Sus dos primeras secciones se ocupan de la organización de la información genealógica de machos y de hembras; la tercera de la información productiva; la cuarta de la elaboración de informes y la quinta es una miscelánea de utilidades y un control de salida, con conexión con otros programas. Las misiones básicas del programa se centran en la emisión de informes productivos oficiales, destinados a la administración y a los ganaderos, y la preparación de la información para su análisis en programas de selección genética

    Local conditions influence thermal sensitivity of pencil urchin populations (Eucidaris galapagensis) in the Galápagos Archipelago

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    The responses of ectothermic organisms to changes in temperature can be modified by acclimatization or adaptation to local thermal conditions. Thus, the effect of global warming and the deleterious effects of extreme heating events (e.g., heatwaves) on the metabolism and fitness of ectotherms can be population specific and reduced at warmer sites. We tested the hypothesis that when environmental temperature is greater, grazer populations in the Galápagos are less thermally sensitive (potentially due to acclimatization or adaptation). We quantified the acute thermal sensitivity of four populations of the pencil sea urchin, Eucidaris galapagensis, by measuring individual oxygen consumption across a range of temperatures. Thermal performance curves were estimated for each population and compared to local thermal conditions 2 months prior to collection. Results indicate that E. galapagensis populations were adapted and/or acclimatized to short-term local temperature as populations at warmer sites had substantially higher thermal tolerances. The acute thermal optimum (Topt) for the warmest and coolest site populations differed by 3 °C and the Topt was positively correlated with maximum temperature recorded at each site. Additionally, temperature-normalized respiration rate and activation energy (E) were negatively related to the maximum temperature. Understanding the temperature-dependent performance of the pencil urchin (the most significant mesograzer in this system), including its population specificity, provides insight into how herbivores and the functions they perform might be affected by further ocean heating

    Adrenalectomía laparoscópica por metástasis metácrona. Experiencia en 12 casos

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    To assess the peroperative and oncological results of laparoscopic adrenalectomy for an isolated metastasis. MATERIAL AND METHODS: A retrospective, descriptive study was conducted of 12 laparoscopic adrenalectomies performed for metastases out of a total of 40 adrenalectomies performed from May 1998 to April 2009. The primary tumor was pulmonary in 7 patients, renal in 3, and colonic in 2. Demographic data collected included median age, operating time, blood loss, complications, tumor size, and length of hospital stay. The Kaplan-Meier method was used to analyze survival. RESULTS: Operating time was 150 min (range, 90-206). Peroperative bleeding was 60 ml (range, 15-150). Peroperative complications occurred in 3% of patients. Tumor size was 4.5 cm (range, 1.3-8.5). No positive margins were seen in the resected specimens. Hospital stay was 3 days (range 3-5). Actuarial survival was 55.6% at 23 months (range, 2-38) with mean and median follow-up times of 20.9 and 23 months. CONCLUSIONS: In selected patients, laparoscopic adrenalectomy for metastasis is a safe procedure with oncological results superimposable to those of open surgery

    Nefrectomía parcial laparoscópica. Análisis de los primeros 30 casos de nuestra serie y revisión de la literatura

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    Objective: Our goal is to analyze the surgical and clinicopathological results of our first 30 laparoscopic partial nephrectomies (LPN) performed consecutively and correlate the results with the literature. Material and methods: This is a cases series, with 30 patients (20 men and 10 women) operated between 2006 and 2008. We assessed the clinicopathological factors and complications. The mean and median follow-up was 25 and 5 months. Results: Resected tumors had an average size of 2.4 cm. 60% of the tumors were malignant. The pathological stage was pT1 in 100% of cases (47% grade I, 53% Fuhrman grade II). Surgical margins were positive in 3 cases, switching to open surgery. Intraoperative bleeding was 74.66 cc (35.7±SD) and 70 cc of mean and median. The mean operative time was 214.4min (±69) and ischemia time of 31.3min (±13.8). Conclusions: Our results are similar to those reported in the literature, except for positive margins and conversion attributable to the learning curve

    Deciphering The Preservation Of Fossil Insects: A Case Study From The Crato Member, Early Cretaceous Of Brazil

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    Exceptionally well-preserved three-dimensional insects with fine details and even labile tissues are ubiquitous in the Crato Member Konservat Lagerstätte (northeastern Brazil). Here we investigate the preservational pathways which yielded such specimens. We employed high resolution techniques (EDXRF, SR-SXS, SEM, EDS, micro Raman, and PIXE) to understand their fossilisation on mineralogical and geochemical grounds. Pseudomorphs of framboidal pyrite, the dominant fossil microfabric, display size variation when comparing cuticle with inner areas or soft tissues, which we interpret as the result of the balance between ion diffusion rates and nucleation rates of pyrite through the originally decaying carcasses. Furthermore, the mineral fabrics are associated with structures that can be the remains of extracellular polymeric substances (EPS). Geochemical data also point to a concentration of Fe, Zn, and Cu in the fossils in comparison to the embedding rock. Therefore, we consider that biofilms of sulphate reducing bacteria (SRB) had a central role in insect decay and mineralisation. Therefore, we shed light on exceptional preservation of fossils by pyritisation in a Cretaceous limestone lacustrine palaeoenvironment. © 2016 Osés et al.20161

    Association of crossed renal ectopia and aortic aneurism. Case report

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    OBJECTIVE: Renal malformations are rare entities and rarely have clinical consequences. Crossed renal ectopia has an incidence of 1/2.000 autopsies. The association with aortic aneurysm is even more exceptional. METHODS: We present our case and perform a bibliographic review. RESULTS: To date and in our knowledge , seven cases of crossed renal ectopia associated with aortic aneurysm were described on the literature. This malformation makes the treatment of the aneurysm more complex. The possibility of renal function decrease caused by injuries to the renal arteries during the surgical procedure is always present. Because of this risk of injury of the kidney during surgery preoperative evaluation of the vascularization must include image technologies as the MRI, CT-angiography or conventional arteriography. During the aortic intervention vascular conservation must be performed and it is necessary to minimize the time of renal ischemia. CONCLUSIONS: The association of crossed renal ectopia and aortic aneurysm is a rare event. The surgical intervention of the aorta does not have to necessarily originate a loss of renal function. Anyway the worsening of the renal clearance must be foreseen
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